[Heavy water (D20) inhibits growth of human xenotransplanted oropharyngeal cancers. An animal experiment study in nude mice].

The large mass ratio of D to H, 2 to 1, gives rise to multiple effects in living organisms, when D is administered as heavy water (D2O). Deuterium at high concentration interferes with cell division and depresses the uptake of DNA-precursors in mammalian cells (Katz et al., 1970). However, the effects of D2O on the organism disappear after cessation of deuteration of the body water. Mammals do not survive more than 35% of D2O substitution for normal water in their body fluids for long periods of time. However, mice drinking 30% D2O have a normal life span and normal body weight (Katz et al., 1970; Hodel et al., 1982). Heavy water also exerts antineoplastic effects. We demonstrated that moderate body deuteration combined with a cytostatic drug significantly increases the survival time of mice bearing transplantable murine neoplasms (Laissue et al., 1982). Hitherto, it is not known whether heavy water affects human neoplasms in the same way. Therefore, we have studied human squamous cell carcinomas of the oropharyngeal region which were xenografted in nude mice. A moderate deuteration of body water of the mice (less than or equal to 20 atom %) drinking 30% D2O, inhibited the tumour growth markedly by a factor of 0.4 to 0.5 compared to the growth of the same tumours in control animals drinking tap water. This effect of D2O seems to be directly proportional to the grade of malignancy of the carcinomas. Histologically, no differences were detectable between the original carcinomas and the tumour grafts in animals with and without D2O.